/*
 * Created on May 27, 2008
 * Created by Paul Gardner
 * 
 * Copyright (C) Azureus Software, Inc, All Rights Reserved.
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License only.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
 */

package org.gudy.azureus2.core3.util;

/**
 * This class DOES NOT COPY THE UNDERLYING BYTES AND ONLY SUPPORTS Short.MAX_VALUE bytes
 * 
 * @author Azureus
 * 
 */

public class HashWrapper2 {
    final private byte[] hash;
    final private short offset;
    final private short length;
    final private int hash_code;

    public HashWrapper2(byte[] hash) {
        this(hash, 0, hash.length);
    }

    public HashWrapper2(byte[] _hash, int _offset, int _length) {
        if (_offset >= Short.MAX_VALUE) {
            throw (new RuntimeException("Illegal value - offset too large"));
        }

        if (_length >= Short.MAX_VALUE) {
            throw (new RuntimeException("Illegal value - length too large"));
        }

        hash = _hash;
        offset = (short) _offset;
        length = (short) _length;

        int hc = 0;

        for (int i = offset; i < offset + length; i++) {

            hc = 31 * hc + hash[i];
        }

        hash_code = hc;
    }

    public final boolean equals(Object o) {
        if (!(o instanceof HashWrapper2)) {

            return false;
        }

        HashWrapper2 other = (HashWrapper2) o;

        if (other.length != length) {

            return (false);
        }

        byte[] other_hash = other.hash;
        int other_offset = other.offset;

        for (int i = 0; i < length; i++) {

            if (hash[offset + i] != other_hash[other_offset + i]) {

                return (false);
            }
        }

        return (true);
    }

    public int hashCode() {
        return (hash_code);
    }
}
